Field of the Invention
The invention relates to a turbine wheel and to a method for the production thereof,
Description of the Related Art
The so-called rotor of a turbocharger has a turbine wheel and the turbocharger shaft which can be connected to the turbine wheel via a weld peg arranged on the back of the turbine wheel. For said connection, it is possible for the shaft and the turbine wheel to be connected to one another using a welding process (for example friction welding or electron beam welding). A turbine wheel TR for such a welding process is illustrated in highly simplified schematic form in FIGS. 4 and 5. The turbine wheel TR has the said wheel back R and a weld peg Z which, after the casting process, is mechanically machined along the dash-dotted line SZ with two recesses for piston rings. The vertical region of the dash-dotted line SZ constitutes the end of the grinding zone. Furthermore, according to FIG. 5, an undercut FS is produced at the transition between the wheel back R and the weld peg in a further machining step, which undercut can be seen from FIG. 5.
FIG. 6 shows, by way of example, an embodiment of a turbine wheel TR which again has a wheel back R and a weld peg Z which can be connected by means of a welding process to the shaft not shown in FIG. 6 (or in FIGS. 4 and 5) of the turbocharger. Out of principle, in the case of said rotor, the additional machining for producing an undercut as shown in FIG. 5 should no longer be necessary. However, tests carried out within the context of the invention have shown that a corner E is formed at the transition between the grinding zone and the non-machined part of the turbine wheel because the grinding disk must maintain a distance from the wheel back R, which can in turn lead to a collision between the rotor and the bearing housing LG.
It is therefore an object of the present invention to provide a turbine wheel and to a method for the production thereof, wherein it should be possible to avoid an additional machining step for creating an undercut in the transition region between the weld peg and the wheel back of the turbine wheel.